Drawing-board attachment



Patented Sept. 11, 1928.

UNITED-.STATES ALFRED P. JACOB, or NEW YORK, n.

DRAWING-BOARD ATTACHMENT. y

Application med March 4, 1927. serial No.' '172,899

This invention relates to a drawing board attachment and has particularreference to` a winding device for regulating the tension on and firmly securing the cable usually provided on drawing boards for permitting the angular adjustment of vparallel* straight edges.` i Q An object of the invention resides 1n the provision of a means `for takingu'p any slack in the cable and at the same time to firmly secure the cable to the board, preventing lateral movement, so that the straight edge may bemaintained in 'a true horizontal position upon the drawing board.

Another' object of the invention is to provide a cable tensioning device: for the above purpose which may be applied todrawing boards now in use without affecting the change of any construction therein.

A further object is to provide a lcable tensioning device which is extremely simple in construction, inexpensive of manufacture, andv ellicient for the purpose intended.

lVith these and other objects in view, the invention resides in certain novel construction and combination and arrangement of parts, the essential features of which are hereinafter fully described, are particularly pointed out in the appended claims, and are illustrated in the accompanying` drawing, in which Figure 1 is a plan view of a drawing board with my attachment mounted thereon.

Figure 2 is an enlarged vertical sectional View on the line 2-2 of Figure 1.

Figure 3 is a sectional view on the line 3-3 of Figure 2.

Figure t is a perspective view of myV device per se and showing the parts in a separated position. .v Y

Figure 5 is a horizontal sectional view on the line 5-5 of Figure 2.

Referring tothe drawing, the reference numeral A designates a drawing board of the ordinary construction and which has a cable B extending therearound adjacent the outer edges thereof and on which a straight edge C is mounted for angular adjustment.

My attachment, is shown in its entirety as at and includes an attaching member or base 11 which is constructed of wood or other light material. The base is provided with a central opening 12 from which a slot 13 extends to one of its edges to provide spaced furcations 14. Openings 15 are provided on opposite sides of the central openv stem.

ing to receive screws or like fastening ele; ments 17 which enter the drawing board A to rigidly support the device thereon. The' .device is mounted on the boardA adjacent its top edge and in the path of the top lead of the cable B. Turnably mounted in the opening 12 and removable therefrom is a Winding stem 18 which includes a knurled head 19 and a reduced shank 2O having a kei-r or slot 2l extending inwardly from the outer vend thereof. The slot is of a thick-` ness to receive thecable Band of a' length @quai te the length of the stem or shank 20; The shank is adapted to frictionally engage the walls of the opening' 13, and for regulating the degree of frictiinl provide a set screw 22 which is threaded into 'one' of the furcations 14 to bring the same into closer engagement Vwith 'each `other to contraet the walls of the opening 12 to increase the friction, or to spread the furcations further apartto reduce the friction between the shank and the walls of said opening as de.- sired. The furcations are yieldable to permit of this adjustment.

ln practice, the winding stem is supported from the base 11 and is brought down over the top lead of the cable B so that the cable is received in the slot or kerf 21 thereby keying the cable to the shank of the winding Y The shank is then inserted into the opening 13 where the same frictionally engages the walls thereof and causes the cable to move to the closed end of the kerf and against the head 19. The head is then given a slight turning movement to cause any slack in the cable to be wound about shank thus pulling the cable taut. The head is then pressed down on the cable l to prevent lateral slipping so as to maintain the straight edge in a perfectly aligned position upon the drawing board. Should the tension of the cable when drawn taut overcome the friction between the winding stem and the walls of' the opening 13, the set screw 21 is actuated to increase the friction to a point sufficient to prevent loosening of the cable. When slack is desired in the cable in order to angularly adjust the straight edge, the winding stem may be turned in an opposite direction to pay out sullicient cable to permit of the adjustment.

From the foregoing description, it will be seen that I have provided a device which vmay be easily attached to a drawing board `now in use and which will till a long felt eny want as draft-smen have found it most difcult to maintain the cable in different tensional conditions. The device is quick-and positive in its actions and will not interfere with the adjustment of thel straight edge nor with the work of a draitsman.`

qWhat is claimed as new is 1. A cable tensioning device for drawing boards comprising a base having an opening therein, and a winding stem having a cable receiving kerf therein and frictionally engageable with the walls of said opening,

, and means for varying the degree of friction between the'winding stem and the walls o said opening.

2. A cable tensioning device for drawing boards comprising a base having an opening thereimsaid base being bifurcated from said opening to one of its edges, a winding element including a head and a reduced shank insertible in said opening for friction al engagement with the walls of said opening, and a cable receiving lierf provided in the free end of said shank.

3. A cable tensioning device for drawing boards comprising a base having an opening therein, said base being bifurcated from said opening to one of its edges, a windingY elementV including a head and a` reduced shank insertible in said opening for'frictional engagement with the walls of said opening, a cable receiving kerf provided in the free end of said shank, and an adjusting screw passing through the furcations formed by said bifurcation for varying the degree vof friction between .said stem and the walls of said opening.

LA cable tensiomng device for drawing lboards comprising a base adapted to be fix- In testimony whereof I have aflixed my signature.V

' ALFRED :En-JACOB. 

